People demonstrate against a U.S.-led strike on Syria in front of the White House in Washington on Saturday. / Nicholas Kamm, AFP/Getty Images

by Laura Petrecca, USA TODAY

by Laura Petrecca, USA TODAY

Protesters worldwide are taking to the streets - and to social media - to express their varied views on a possible U.S.-led attack on Syria.

The debate about such an attack has grown as politicians and the public vocalize their thoughts on what penalty Syrian President Bashar Assad should pay for his alleged use of chemical weapons against civilians on Aug. 21.

U.N. chemical weapons experts are working to determine what exactly occurred in an area near Damascus that day, but the U.S. released a report Friday laying out evidence that Assad sanctioned a chemical attack that killed more than 1,420 people.

On Saturday afternoon, President Obama said he was in favor of taking military action against Assad, but said an attack would be limited in "duration and scope," and he would seek congressional approval for the use of force.

Just before the president's announcement, shouts from hundreds of activists demonstrating against military action could be heard outside the White House's Rose Garden. At the same time, about 50 counter-protesters nearby advocated for U.S. action in Syria, according to Politico.com.

On Saturday, there were also protests in New York City and Boston, as well as one planned in Houston.

Protesters also took to the streets in international locations. In London, more than 1,000 people carrying Syrian flags and placards reading "Hands Off Syria" marched to Downing Street and rallied in Trafalgar Square.

About 700 people turned out for an anti-war demonstration in Frankfurt, police said.

At a protest organized by left-wing opposition parties in Amman, Jordan, activist Kawthar Arrar described any military intervention as "an aggression on the whole Arab world." Protesters there gathered outside the U.S. Embassy, chanting slogans and setting fire to American and Israeli flags.

On Twitter, hundreds of social media users quickly posted reactions under the #Syria hashtag after Obama spoke. British Prime Minister David Cameron himself weighed in, tweeting: "I understand and support Barack Obama's position on #Syria."

Earlier this week, Cameron lost his case for military action when the United Kingdom parliament voted against British participation in any U.S.-led attack against Syria.

In the U.S., nearly 80% of Americans said President Obama should seek congressional approval before taking military action, according to an NBC News poll conducted on Wednesday and Thursday.

Overall, 50% of Americans said they oppose the United States taking military action against Assad, and 42% said they support it, according to the poll.